1. Field of the Invention
The invention relates to methods of treating allergic rhinitis.
2. Description of the Prior Art
Allergic rhinitis is a perennial or seasonal condition characterized by a runny, itchy nose, watery, itchy eyes, congestion, postnasal drip and associated symptoms. The basic cause of this syndrome is environmental exposure to, and inhalation of, allergens.
The treatment of choice for allergic rhinitis is avoidance of the allergens. Total avoidance of certain allergens, for example tree or weed pollens or mold spores, is virtually impossible, however, and non-specific drug treatment of allergic rhinitis is often utilized.
The most widely used agents for the treatment of allergic rhinitis are antihistamines of the H.sub.1 -receptor antagonist type. These agents provide some symptomatic relief of nasal and ocular itching, sneezing, rhinorrhea and excess lacrimation, but are not particularly effective in relieving congestion or postnasal drip, and many antihistamines suffer from drawbacks such as short duration of activity and side effects including drowsiness. Moreover, for maximal effectiveness, the antihistamines must be taken regularly and prophylactically.
Vasoconstricting agents are often administered alone or in conjunction with antihistamines to act as decongestants in the treatment of allergic rhinitis. Numerous untoward side effects have been associated with persistent use of such decongestants, and these drugs may act synergistically with antihistamines to produce further side effects not evident where each class of agents is administered alone. Vasoconstricting agents administered topically to the nasal passages in the form of nosedrops or spray do act to temporarily relieve nasal stuffiness, but often lead to "rebound" congestion and rhinitis medicamentosa after uncontrolled usage.
Another pharmaceutical agent that has been administered topically in the nose for treatment of allergic rhinitis is cromolyn sodium. The topical application of cromolyn sodium is moderately effective, particularly on a prophylactic basis, but burning and stinging of the nasal lining has been reported when cromolyn is used during an acute phase of rhinitis.
Corticosteroids have been administered orally, parenterally and topically for the treatment of allergic rhinitis, and often achieve dramatic effects. However, the well-known side effects of this group of drugs prevents use of the corticosteroids on a long-term basis except in very severe cases. Nasal sprays containing corticosteroids have also been utilized but may also cause systemic side effects due to absorption through the nasal mucosa.